The Biodiversity Gradient Experiment was a long-term study that examined the impact of plant diversity on the delivery of ecosystem services from annual cropping systems. It consisted of 21 different experimental treatments ranging from bare soil to continuous corn, soybean or wheat—without or with a cover crop, to mixed rotations of these crops—without or with cover crops(s), to annually fallowed fields with early successional plant communities. Species richness across these treatments ranged from 0, 1, 2, 3, 4, 5 to >15 in a 3-year rotation cycle.
The experiment was established in 2000 at the LTER Main Site. Treatment plots were 9 x 27 m and replicated in each of 4 randomized blocks. See the plot map for treatment codes and descriptions. Management was based on the Biologically Based treatment of the Main Cropping System Experiment. Lysimeters (soil water samplers) were installed in 24 plots.
The experiment was retired after the 2019 harvest and planted to sorghum in 2020.